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21.
The thermal behaviour of (NH4)3VO2F4 and Na(NH4)2VO2F4 was investigated using TG, DTA and DSC techniques. The occurrence of a first order phase transition with the onset of decomposition in both the compounds is confirmed. The temperature, energetics and hysteresis of the transition are obtained. A possible path for the thermal degradation is given for both the compounds, and the residues are identified. 相似文献
22.
M. F. Horstemeyer J. Lathrop A. M. Gokhale M. Dighe 《Theoretical and Applied Fracture Mechanics》2000,33(1)
Internal state variable rate equations are cast in a continuum framework to model void nucleation, growth, and coalescence in a cast Al–Si–Mg aluminum alloy. The kinematics and constitutive relations for damage resulting from void nucleation, growth, and coalescence are discussed. Because damage evolution is intimately coupled with the stress state, internal state variable hardening rate equations are developed to distinguish between compression, tension, and torsion straining conditions. The scalar isotropic hardening equation and second rank tensorial kinematic hardening equation from the Bammann–Chiesa–Johnson (BCJ) Plasticity model are modified to account for hardening rate differences under tension, compression, and torsion. A method for determining the material constants for the plasticity and damage equations is presented. Parameter determination for the proposed phenomenological nucleation rate equation, motivated from fracture mechanics and microscale physical observations, involves counting nucleation sites as a function of strain from optical micrographs. Although different void growth models can be included, the McClintock void growth model is used in this study. A coalescence model is also introduced. The damage framework is then evaluated with respect to experimental tensile data of notched Al–Si–Mg cast aluminum alloy specimens. Finite element results employing the damage framework are shown to illustrate its usefulness. 相似文献
23.
M. F. Horstemeyer Ken Gall K. W. Dolan A. Waters J. J. Haskins D. E. Perkins A. M. Gokhale M. D. Dighe 《Theoretical and Applied Fracture Mechanics》2003,39(1):23-45
Void nucleation, growth, and coalescence in A356 aluminum notch specimens was determined from a combination of experiments, finite element analysis, nondestructive analysis, and image analysis. Notch Bridgman tension experiments were performed on specimens to failure and then other specimens were tested to 90%, 95%, and 98% of the failure load. The specimens were evaluated with nondestructive X-ray tomography and optical image analysis. Finite element simulations of the notch tests were performed with an elastic–plastic internal state variable material model that incorporated the pertinent microstructures (silicon particle volume fraction and size distribution and porosity volume fraction and size distribution). Parametric finite element simulations were performed to give insight into various initial conditions and responses of the notch tensile bars. The various methods all corroborated the same damage progression. 相似文献
24.
A. K. Singhvi G. N. Rao T. M. Srinivasan K. V. G. K. Gokhale 《Hyperfine Interactions》1986,29(1-4):1161-1164
Mossbauer effect studies on some natural magnetite ore samples from India are reported for the first time. Using the Mossbauer
spectroscopy data, the magnetites of sedimentary origin are differentiated from those of igneous origin. The igneous magnetites
are found to have a nearly stoichiometric composition. A titanium enrichment in these samples was also evidenced. The magnetites
of sedimentary origin, however, have almost fully oxidized to haematite. 相似文献
25.
B.M. Arora A. Majumdar A.P. Shah M.R. Gokhale S. Ghosh A. Bhattacharya D. Sengupta 《Infrared Physics & Technology》2007,50(2-3):206-210
Higher responsivity of quantum well infrared photodetectors based on In0.53Ga0.47As–InP material system compared to the well established GaAs–AlGaAs material system is analyzed. It is shown that the higher responsivity of the former results mainly from its smaller capture probability, pc, than that of the latter. Both transport as well as L valley occupancy appear important in determining the pc. 相似文献
26.
de Oliveira Maida Aysla Costa Ficca Valerio C. A. Gokhale Rohan Santoro Carlo Mecheri Barbara D’Epifanio Alessandra Licoccia Silvia Atanassov Plamen 《Journal of Solid State Electrochemistry》2021,25(1):93-104
Journal of Solid State Electrochemistry - In this work, we initially report a detailed advancement in the utilization of metal-N4 chelate macrocycles in the oxygen reduction reaction (ORR). Then,... 相似文献
27.
Analytical and numerical study of the stability of sheet electron beam in periodically cusped magnetic field (PCM) is made.
The beam has been considered as having diffused density profile. The conditions for beam focusing are discussed. 相似文献
28.
A series of 5-(arylthio)-2,4-diaminoquinazolines are known as selective inhibitors of dihydrofolate reductase (DHFR) from Candida albicans. We have performed docking and molecular dynamics simulations of these inhibitors with C. albicans and human DHFR to understand the basis for selectivity of these agents. Study was performed on a selected set of 10 compounds with variation in structure and activity. Molecular dynamics simulations were performed at 300 K for 45 ps with equilibration for 10 ps. Trajectory data was analyzed on the basis of hydrogen bond interactions, energy of binding and conformational energy difference. The results indicate that hydrogen bonds formed between the compound and the active site residues are responsible for inhibition and higher potency. The selectivity index, i.e the ratio of I50 against human DHFR to I50 against fungal DHFR, is mainly determined by the conformation adapted by the compounds within the active site of two enzymes. Since the human DHFR active site is rigid, the compound is trapped in a higher energy conformation. This energy difference between the two conformations E mainly governs the selectivity against fungal DHFR. The information generated from this analysis of potency and selectivity should be useful for further work in the area of antifungal research. 相似文献
29.
30.
The copper complex [KGHK-Cu]+ demonstrates catalytic inactivation of human angiotensin converting enzyme at sub-saturating concentrations, under oxidative conditions, with an observed rate constant k approximately 2.9 +/- 0.5 x 10(-2) min(-1). 相似文献